Field of the Disclosure
Embodiments of the present disclosure relate to an organic light emitting display device, and more particularly, to a top emission type organic light emitting display device, and a method of manufacturing the same.
Discussion of the Related Art
An organic light emitting display (OLED) device, which is a self light emitting display device, has advantages of low power consumption, rapid response speed, high emission efficiency, high luminance and wide viewing angle.
According to a direction of light emitted from an organic light emitting device, the OLED device may be largely classified into a top emission type and a bottom emission type. In case of the bottom emission type, a circuit device is disposed between an emitting layer and an image displaying surface, whereby an aperture ratio may be lowered due to the circuit device. Meanwhile, in case of the top emission type, a circuit device is not disposed between an emitting layer and an image displaying surface, whereby an aperture ratio may be improved.
FIG. 1 is a cross sectional view of a related art top emission type OLED device.
As shown in FIG. 1, a thin film transistor layer (T) including an active layer 11, a gate insulating film 12, a gate electrode 13, an insulating interlayer 14, a source electrode 15, and a drain electrode 16 is provided on an active area (AA) of a substrate 10, and then a passivation layer 20 and a planarization layer 30 are sequentially provided on the thin film transistor layer (T).
Also, an anode electrode 40 and an auxiliary electrode 50 are provided on the planarization layer 30. The auxiliary electrode 50 is provided to lower a resistance of a cathode electrode 80 to be explained later.
On the anode electrode 40 and the auxiliary electrode 50, a bank 60 is provided to define a pixel region. Also, an organic light emitting layer 70 is provided in the pixel region defined by the bank 60, and the cathode electrode 80 is provided on the organic light emitting layer 70.
In case of the top emission type, light emitted from the organic light emitting layer 70 passes through the cathode electrode 80. For this reason, the cathode electrode 80 is formed of a transparent conductive material, which causes the increase of resistance of the cathode electrode 80. In order to lower the resistance of the cathode electrode 80, the cathode electrode 80 is connected with the auxiliary electrode 50.
On a pad area (PA) of the substrate 10, there are the gate insulating film 12 and the insulating interlayer 14. A signal pad 90 is provided on the insulating interlayer 14, and the passivation layer 20 is provided on the signal pad 90. A hole is provided in the passivation layer 20 so that the signal pad 90 is exposed to the external via the hole. In order to connect the signal pad 90 with an external driving circuit, the hole is provided in the passivation layer 20 so as to expose the signal pad 90 to the external.
However, the related art top emission type organic light emitting display device may have the following disadvantages.
In order to connect the signal pad 90 with the external driving circuit, the upper surface of the signal pad 90 is exposed to the environment. Accordingly, the upper surface of the signal pad 90 may be corroded, and furthermore the corrosion of the signal pad 90 may spread to other regions. In order to prevent the upper surface of the signal pad 90 from being corroded, a metal layer with superior corrosion resistance may be additionally provided on the upper surface of the signal pad 90. In this case, an additional process has to be carried out.
Also, in order to connect the signal pad 90 with the external driving circuit, the hole is provided in the passivation layer 20, and the upper surface of the signal pad 90 is exposed via the hole of the passivation layer 20. In this case, an etchant provided for patterning the anode electrode 40 may flow into the hole provided in the passivation layer 20, whereby the signal pad 90 may be damaged by the etchant. In order to prevent the signal pad 90 from being damaged by the etchant, a process of forming the hole for exposing the upper surface of the signal pad 90 may be carried out additionally after a process of patterning the anode electrode 40, which causes inconvenience of an additional mask process.